This application claims priority from R.O.C. Patent Application No. 090110911, filed May 8, 2001, the entire disclosure of which is incorporated herein by reference.
The present invention relates to a system for sensing the position of a spin dryer cover and, more particularly, to a system that prevents collision between a mechanical arm used to retrieve wafers from the spin dryer and the spin dryer cover.
FIG. 1 shows a structural diagram of a conventional spin dryer cover. The spin dryer 1 comprises a cover 11, a spin dryer tank 12, a linkage 13, a cylinder 14, and a cylinder sensor 141. The cylinder 14 may be hydraulically or pneumatically driven, but may also be driven electrically, mechanically, or the like.
To operate the spin dryer 1, the cylinder 14 pulls the linkage 13 back so that the cover 11 closes the spin dryer tank 12 for spin drying. After spin drying, the cylinder 14 pushes the linkage 13 forward so that the cover 11 separates from the spin dryer tank 12 to open up the dryer tank 12. A mechanical arm then moves into the spin dryer tank 12 to retrieve the wafer(s) from the spin dryer tank 12.
FIG. 2 shows a cover sensor circuit of the spin dryer 1. The cover sensor circuit includes a cylinder sensor 141. When the cylinder pushes forward, the cylinder sensor 141 sends a cover opening signal to a control circuit 3.
In the above-described conventional cover sensing system, the mechanical arm may sometimes collide with the cover. In FIG. 1 and FIG. 2, since the cover sensing system senses the position of the cover 11 only by feedback of the cylinder sensor 14, the control circuit 3 still receives the cover opening signal and engages the mechanical arm to remove the wafer even when the linkage 13 or another component malfunctions and the cylinder pushes forward but the cover 11 remains unopened. In that case, the mechanical arm can collide with the cover 11, causing serious damage.
Embodiments of the present invention are directed to a system for sensing the position of a spin dryer cover. The cover opens and closes dependent upon the first operation of the cylinder to open the dryer cover and the second operation of the cylinder to close the dryer cover. The system for sensing the position of a spin dryer cover comprises a cylinder, a cover sensor and a logic circuit. The cylinder sensor senses the first and second operations of the cylinder. The cover sensor detects whether the cover is open or closed. When the first operation of the cylinder has registered with the cylinder sensor and the cover sensor has deduced that the cover has opened, the logic circuit outputs a cover opening signal.
In an apparatus for spin drying substrates in a spin dryer tank, a spin dryer cover is movable between a closed position to close an opening of the spin dryer tank and an open position to open the spin dryer tank, and a cylinder is coupled with the spin dryer cover. The cylinder is movable in a first operation to move the spin dryer cover to the open position and movable in a second operation to move the spin dryer cover to the closed position. One aspect of the present invention is directed to a system for sensing the position of the spin dryer cover comprising a cylinder sensor configured to sense the first operation and the second operation of the cylinder. A cover sensor is configured to sense the position of the spin dryer cover. A logic circuit is configured to output a cover opening signal indicating that the spin dryer cover is in the open position when the cylinder sensor senses the first operation of the cylinder and the cover sensor senses that the spin dryer cover is in the open position.
In some embodiments, the cylinder sensor is configured to sense the first operation when the cylinder is pushed forward. The cylinder sensor is configured to sense the second operation when the cylinder is pulled backward. The cover opening signal is directed to a control circuit which operates a mechanical arm in response to the cover opening signal to enter the spin dryer tank through the opening of the spin dryer tank. The cylinder sensor outputs a first sensing signal to the logic circuit when the cylinder sensor senses the first operation of the cylinder, and the cover sensor outputs a second sensing signal to the logic circuit when the cover sensor senses that the spin dryer cover is in the open position.
In specific embodiments, the logic circuit is a relay comprising a signal terminal configured to receive the second sensing signal from the cover sensor, an input terminal configured to receive the first sensing signal from the cylinder sensor, and an output terminal configured to output the first sensing signal received by the input terminal as the cover opening signal when the control signal terminal receives the second sensing signal. The relay may comprise a solenoid loop that connects with the control signal terminal; and a switch connecting between the input terminal and the output terminal. The system may comprise a bypass switch which is connected to the cylinder sensor and is configured to receive the first sensing signal directly from the cylinder sensor. The bypass switch is movable to a closed position to bypass the logic circuit and output the first sensing signal from the cylinder sensor as the cover opening signal.
Another aspect of the invention relates to an apparatus for spin drying substrates in a spin dryer tank, wherein a spin dryer cover is movable between a closed position to close an opening of the spin dryer tank and an open position to open the spin dryer tank, wherein a cylinder is coupled with the spin dryer cover, the cylinder movable in a first operation to move the spin dryer cover to the open position and movable in a second operation to move the spin dryer cover to the closed position, and wherein a control circuit is operatively coupled with a mechanical arm to control the arm to move into and out of the spin dryer tank through the opening of the spin dryer tank. A system for sensing the position of the spin dryer cover comprises a cylinder sensor configured to sense the first operation and the second operation of the cylinder, and a cover sensor configured to sense the position of the spin dryer cover. A logic circuit is configured to output a cover opening signal to the control circuit indicating that the spin dryer cover is in the open position when the cylinder sensor senses the first operation of the cylinder and the cover sensor senses that the spin dryer cover is in the open position. The control circuit operates the mechanical arm in response to the cover opening signal to enter the spin dryer tank through the opening of the spin dryer tank.
Another aspect of the present invention relates to an apparatus for spin drying substrates in a spin dryer tank, wherein a spin dryer cover is movable between a closed position to close an opening of the spin dryer tank and an open position to open the spin dryer tank, and wherein a cylinder is coupled with the spin dryer cover, the cylinder movable in a first operation to move the spin dryer cover to the open position and movable in a second operation to move the spin dryer cover to the closed position. A system for sensing the position of the spin dryer cover comprises a cylinder sensor configured to sense the first operation and the second operation of the cylinder, and a cover sensor configured to sense the position of the spin dryer cover. A logic circuit is configured to output a cover opening signal indicating that the spin dryer cover is in the open position when the cylinder sensor senses the first operation of the cylinder and the cover sensor senses that the spin dryer cover is in the open position. A bypass switch is connected to the cylinder sensor and is configured to receive the first sensing signal directly from the cylinder sensor. The bypass switch is movable to a closed position to bypass the logic circuit and output the first sensing signal from the cylinder sensor as the cover opening signal.